setenv.c revision 31de2854 
1/*	$OpenBSD: setenv.c,v 1.13 2010/08/23 22:31:50 millert Exp $ */
2/*
3 * Copyright (c) 1987 Regents of the University of California.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <errno.h>
32#include <stdlib.h>
33#include <string.h>
34
35char *__findenv(const char *name, int len, int *offset);
36
37extern char **environ;
38static char **lastenv;				/* last value of environ */
39
40/*
41 * putenv --
42 *	Add a name=value string directly to the environmental, replacing
43 *	any current value.
44 */
45int
46putenv(char *str)
47{
48	char **P, *cp;
49	size_t cnt;
50	int offset = 0;
51
52	for (cp = str; *cp && *cp != '='; ++cp)
53		;
54	if (*cp != '=') {
55		errno = EINVAL;
56		return (-1);			/* missing `=' in string */
57	}
58
59	if (__findenv(str, (int)(cp - str), &offset) != NULL) {
60		environ[offset++] = str;
61		/* could be set multiple times */
62		while (__findenv(str, (int)(cp - str), &offset)) {
63			for (P = &environ[offset];; ++P)
64				if (!(*P = *(P + 1)))
65					break;
66		}
67		return (0);
68	}
69
70	/* create new slot for string */
71	for (P = environ; *P != NULL; P++)
72		;
73	cnt = P - environ;
74	P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
75	if (!P)
76		return (-1);
77	if (lastenv != environ)
78		memcpy(P, environ, cnt * sizeof(char *));
79	lastenv = environ = P;
80	environ[cnt] = str;
81	environ[cnt + 1] = NULL;
82	return (0);
83}
84
85/*
86 * setenv --
87 *	Set the value of the environmental variable "name" to be
88 *	"value".  If rewrite is set, replace any current value.
89 */
90int
91setenv(const char *name, const char *value, int rewrite)
92{
93	char *C, **P;
94	const char *np;
95	int l_value, offset = 0;
96
97	for (np = name; *np && *np != '='; ++np)
98		;
99#ifdef notyet
100	if (*np) {
101		errno = EINVAL;
102		return (-1);			/* has `=' in name */
103	}
104#endif
105
106	l_value = strlen(value);
107	if ((C = __findenv(name, (int)(np - name), &offset)) != NULL) {
108		int tmpoff = offset + 1;
109		if (!rewrite)
110			return (0);
111#if 0 /* XXX - existing entry may not be writable */
112		if (strlen(C) >= l_value) {	/* old larger; copy over */
113			while ((*C++ = *value++))
114				;
115			return (0);
116		}
117#endif
118		/* could be set multiple times */
119		while (__findenv(name, (int)(np - name), &tmpoff)) {
120			for (P = &environ[tmpoff];; ++P)
121				if (!(*P = *(P + 1)))
122					break;
123		}
124	} else {					/* create new slot */
125		size_t cnt;
126
127		for (P = environ; *P != NULL; P++)
128			;
129		cnt = P - environ;
130		P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
131		if (!P)
132			return (-1);
133		if (lastenv != environ)
134			memcpy(P, environ, cnt * sizeof(char *));
135		lastenv = environ = P;
136		offset = cnt;
137		environ[cnt + 1] = NULL;
138	}
139	if (!(environ[offset] =			/* name + `=' + value */
140	    malloc((size_t)((int)(np - name) + l_value + 2))))
141		return (-1);
142	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
143		;
144	for (*C++ = '='; (*C++ = *value++); )
145		;
146	return (0);
147}
148
149/*
150 * unsetenv(name) --
151 *	Delete environmental variable "name".
152 */
153int
154unsetenv(const char *name)
155{
156	char **P;
157	const char *np;
158	int offset = 0;
159
160	if (!name || !*name) {
161		errno = EINVAL;
162		return (-1);
163	}
164	for (np = name; *np && *np != '='; ++np)
165		;
166	if (*np) {
167		errno = EINVAL;
168		return (-1);			/* has `=' in name */
169	}
170
171	/* could be set multiple times */
172	while (__findenv(name, (int)(np - name), &offset)) {
173		for (P = &environ[offset];; ++P)
174			if (!(*P = *(P + 1)))
175				break;
176	}
177	return (0);
178}
179